Radial force density and vibration characteristics of modular permanent magnet brushless AC machine

The radial force density harmonics and vibrational characteristics of a three-phase modular permanent magnet brushless AC machine is investigated. It is shown that, owing to the presence of a large number of low- and high-order stator space harmonic magnetomotive forces, modular machines are more likely to exhibit higher low-frequency vibrations than conventional permanent magnet brushless machines. Experimental results support the analysis and its findings.